Saponified ethylene-vinyl acetate copolymers (hereinafter referred to as “EVOH”) are excellent in melt moldability, gas barrier properties, water resistance, oil resistance, antistatic property and mechanical strength, and are used as various types of packages in the form of a film, a sheet, a container or the like. In these packages, visible imperfections generated at the time of molding, e.g. discoloration, fish eyes, rough surfaces, etc., are significant problems that should be overcome.
On the other hand, to reduce production cost, it is desirable to recover and reuse unreacted materials and used solvents in the process of producing EVOH. Particularly, in the production of EVOH on commercial scale, it is desirable to recover unreacted vinyl acetate from a solution after copolymerizing ethylene and vinyl acetate (for example, see JP 45(1970)-3388B).